diff options
| author |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-05-12 07:42:20 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-07-12 15:38:52 -0700 |
| commit | a2165e416878b325747f871df4b236b49bf61486 (patch) | |
| tree | f34e198b527f5a69380b72a311076e1f26e26268 /include/trace | |
| parent | doc: Update RCU CPU stall-warning documentation (diff) | |
| download | linux-dev-a2165e416878b325747f871df4b236b49bf61486.tar.xz linux-dev-a2165e416878b325747f871df4b236b49bf61486.zip | |
rcu: Don't funnel-lock above leaf node if GP in progress
The old grace-period start code would acquire only the leaf's rcu_node
structure's ->lock if that structure believed that a grace period was
in progress. The new code advances to the leaf's parent in this case,
needlessly acquiring then leaf's parent's ->lock. This commit therefore
checks the grace-period state after marking the leaf with the need for
the specified grace period, and if the leaf believes that a grace period
is in progress, takes an early exit.
Reported-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Add "Startedleaf" tracing as suggested by Joel Fernandes. ]
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/events/rcu.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 7d3650cc9d30..5ab1df0a2801 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -91,8 +91,8 @@ TRACE_EVENT(rcu_grace_period, * * "Startleaf": Request a grace period based on leaf-node data. * "Prestarted": Someone beat us to the request - * "Startedleaf": Leaf-node start proved sufficient. - * "Startedleafroot": Leaf-node start proved sufficient after checking root. + * "Startedleaf": Leaf node marked for future GP. + * "Startedleafroot": All nodes from leaf to root marked for future GP. * "Startedroot": Requested a nocb grace period based on root-node data. * "NoGPkthread": The RCU grace-period kthread has not yet started. * "StartWait": Start waiting for the requested grace period. |